The thing with the colors of all lights is that they can not be "emergency" color lights... at least from my understanding... so blue, yellow, amber, red are out of the question for sure

You are correct. Only emergency vehicle's are allowed to run those colors legally on the highway. I have even seen an officer ask a guy who had a lightbar (knightrider style) that was multi colored if he had a permit for the lights. The car was just sitting in the parking deck at the Camaro's for Hero's host hotel. He said it half jokingly but in a serious manner if that makes sense.

Depending on your state they have color restrictions, but main reason is because they can be a distraction to other drivers. I know here in California that Red and Blue lights on your car are illegal, which is true with most states. Also here which im not sure with other states is you cant have them on like underbody kits, etc. while the car is in drive. This is kinda the same reason that you cant drive and play a DVD on your deck.

Not a "LEO" but I am more familiar with Automotive lighting then I would sometimes like to be. All aspects of your vehicles exterior lighting are strictly regulated by federal law. That includes, mounting height, color, number of each function, light output, visibility angles..... and an endless number of other things that go into packaging lamps during the up front design process of each vehicle. Add in European regulations with variations of those for China and Korea...... it's an endless list of regulations.